Solar guide
Solar panel output calculator
Estimate daily, monthly and annual solar production from system size, peak sun hours and a real-world performance ratio.
Solar panel output is normally estimated from the installed system size, the average daily peak sun hours in your location, and a performance ratio that accounts for real-world losses. For the full calculation logic, see the methodology page.
Quick output estimate
Change the values to estimate production for any solar array size.
Estimated production
For savings and payback, use the full calculator after estimating output.
Open full calculatorAnnual output = system size kW × peak sun hours/day × 365 × performance ratioExample solar output by system size
| System size | Daily output | Annual output |
|---|---|---|
| 3 kW | about 10.8 kWh/day | about 3,942 kWh/year |
| 5 kW | about 18.0 kWh/day | about 6,570 kWh/year |
| 10 kW | about 36.0 kWh/day | about 13,140 kWh/year |
Examples assume 4.5 peak sun hours and an 80% performance ratio. Actual output varies with roof angle, shading, temperature, inverter losses and local climate.
What reduces solar panel output?
- Shading from trees, chimneys, walls or nearby buildings.
- Poor roof orientation or tilt.
- High panel temperatures.
- Inverter and wiring losses.
- Dirt, dust, salt and panel degradation.
Solar output FAQ
What are peak sun hours?
Peak sun hours represent usable solar energy in a day, expressed as equivalent full-strength sunlight hours.
Why use a performance ratio?
It accounts for real-world losses such as heat, inverter efficiency, wiring, dirt and panel mismatch.
Is monthly output always the same?
No. Production normally rises in sunnier months and falls in winter or cloudy periods.
Can I use this for any country?
Yes, but use peak sun hours suitable for the location you are estimating.